[ic] Change Formula of [total-cost] and [salestax]

[interchange-users@icdevgroup.org (Josef Strasser-Leitner)]

Hey everyone,

I want to show the VAT in my checkout.hmtl (end also in the e-mails
receipt). This I checked (not really, because the formual of the shwon vat
is wrong). But I want for total-price not the sum of sub-total and VAT
because all my prices in the product table already  include the tax. Where
can I change the formula of [total-cost] (and also of the [salestax])? I
didn't found it.

Any help will be appreciated.
I'm currently using Interchange 4.8.3.

Josef Strasser-Leitner